pvTx properties for carbon dioxide (CO2)/difluoromethane (R32)/1,1,1,2-tetrafluoroethane (R134a) ternary mixture measured in the compressed liquid, superheated vapour, and two-phase regions

In low-temperature refrigeration applications, mixtures containing carbon dioxide and refrigerants with low triple points are considered potential substitutes for the refrigerant R23, characterised by a very high global warming potential. This study provides pvTx measurements for the ternary mixture of carbon dioxide (CO2), difluoromethane (R32), and 1,1,1,2-tetrafluoroethane (R134a) carried out in the compressed liquid, superheated vapour, and two-phase regions. A vibrating tube densimeter was used to measure the compressed liquid density along eight isotherms evenly spaced from (283.15 to 353.15) K and for pressures from near saturation up to 35 MPa. An isochoric apparatus was used to measure the two-phase and superheated vapour pvTx properties along three isochores from (223.15 to 303.15) K. The measurement uncertainties were estimated to be lower than 1 kg∙m −3 for the liquid density and 0.02 m3∙kg−1 for the vapour specific volume. All the presented properties were compared with the calculations of the multi-fluid Helmholtz-energy explicit model. Both the default binary interaction parameters available in REFPROP 10.0 and new binary interaction parameters tuned on the presented data and the experimentally-determined thermodynamic properties collected from the literature have been used in the model. The tuned parameters provided lower deviations than the default parameters used in REFPROP 10.0.